U.S. patent application number 13/437284 was filed with the patent office on 2012-10-04 for catheter for minimally invasive cardiac pacing surgery and method of use.
This patent application is currently assigned to UNIVERSITY OF MEDICINE AND DENTISTRY OF NEW JERSEY. Invention is credited to Jonathan Kraidin, Enrique Pantin.
Application Number | 20120253280 13/437284 |
Document ID | / |
Family ID | 46928178 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120253280 |
Kind Code |
A1 |
Pantin; Enrique ; et
al. |
October 4, 2012 |
CATHETER FOR MINIMALLY INVASIVE CARDIAC PACING SURGERY AND METHOD
OF USE
Abstract
An assembly of a pulmonary venting catheter and a pacing wire
disposed therethrough whereby the pacing wire is extended from the
distal end of the catheter tube during pacing mode, eliminating the
need for exchanging the venting catheter with a pacing catheter to
begin pacing after venting. The pacing wire includes a flexible
distal end for a first conductor to conductively engage heart
tissue after the pacing wire is extended from the catheter distal
end; a second conductor, also exposed outside the catheter distal
end, completes the circuit. The pacing wire is lockable in
unextended and extended positions at the proximal end portion of
the assembly. A method for venting and pacing a patient's heart
during cardiac surgery is described, which includes retracting the
catheter distal end from the pulmonary artery after venting mode,
into the right ventricle during pacing mode, whereafter the pacing
wire is extended for pacing.
Inventors: |
Pantin; Enrique; (Monmouth
Junction, NJ) ; Kraidin; Jonathan; (Milestone
Township, NJ) |
Assignee: |
UNIVERSITY OF MEDICINE AND
DENTISTRY OF NEW JERSEY
Somerset
NJ
|
Family ID: |
46928178 |
Appl. No.: |
13/437284 |
Filed: |
April 2, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61470779 |
Apr 1, 2011 |
|
|
|
Current U.S.
Class: |
604/96.01 ;
607/122 |
Current CPC
Class: |
A61N 1/362 20130101;
A61M 25/007 20130101; A61M 25/0026 20130101; A61N 1/056 20130101;
A61M 2025/0003 20130101; A61M 25/104 20130101 |
Class at
Publication: |
604/96.01 ;
607/122 |
International
Class: |
A61M 25/10 20060101
A61M025/10; A61N 1/05 20060101 A61N001/05 |
Claims
1. A medical apparatus for use during cardiopulmonary bypass
surgery of a patient, comprising: a venting catheter comprising a
flexible elongate shaft having a distal end, a proximal end, and an
inner venting lumen, extending from the proximal end to an inlet
port at the distal end configured to withdraw blood from a
pulmonary artery, the shaft having a length selected to allow the
distal end to be positioned in the pulmonary artery with the
proximal end extending transluminally to a central vein and out of
the patient through a puncture in the central vein; a pacing wire
disposed within said shaft and being movable axially therealong
between a first, retracted position and a second, extended
position; wherein the apparatus is insertable into the vasculature
and heart of a patient for pulmonary venting in a venting mode,
during which the pacing wire is within the venting lumen of the
catheter tube at the first position, and for pacing of the heart in
a pacing mode subsequent to the venting mode, during which the
pacing wire is extended from the venting lumen of the catheter tube
to the second position to engage intracardial tissue of the heart
for pacing thereof.
2. The medical apparatus of claim 1 further comprising an
inflatable balloon having an interior mounted at the distal end of
the shaft.
3. The medical apparatus of claim 2, wherein the venting catheter
further comprises an inflation lumen extending from the proximal
end to an opening near the distal end in communication with the
interior of the balloon.
4. The medical apparatus of claim 1, wherein the pacing wire is
disposed within the inner venting lumen.
5. The medical apparatus of claim 1, wherein the pacing wire
comprises: a distal end portion that is flexible and resilient
along its length, the distal end portion having a flexible
electrode that is exposed when the pacing wire is in the second
position whereby current can be passed between the electrode and
the heart, and further comprising a flexible region located
adjacent to and proximally of the flexible electrode with the
flexibility of the region tapering as the region extends
proximally; and a length of wire conductor being wound into a coil
to form the flexible region and at least a part of the flexible
electrode.
6. The medical apparatus of claim 5, wherein the axial spacing
between the turns of the coil at the flexible region increases as
the flexible region extends proximally.
7. The medical apparatus of claim 5, wherein the wire is of a
progressively increasing cross-sectional area as the wire extends
proximally in the flexible region.
8. The medical apparatus of claim 5, wherein the pacing wire
further comprises a proximal electrode spaced proximally from the
flexible electrode.
9. The medical apparatus of claim 8, wherein the pacing wire
further comprises a conductive wire having a plurality of coils in
which a region of the coils are exposed to define the proximal
electrode.
10. The medical apparatus of claim 1, wherein the pacing wire
further comprises at least one marking to indicate the axial
position of the pacing wire within the shaft.
11. A method for treatment of a patient undergoing cardiopulmonary
bypass surgery, comprising the steps of: providing an apparatus
comprising a venting catheter assembly including a flexible
catheter tube having a distal end, a proximal end, and an inner
venting lumen, extending from the proximal end to an inlet port at
the distal end configured to withdraw blood from a pulmonary
artery, and further comprising a pacing wire within the catheter
tube extending to a distal wire end, the pacing wire being movable
axially within and along the catheter tube between first and second
positions; inserting a distal portion of the catheter tube into the
vasculature and into the heart of a patient such that the catheter
tube distal end accesses the pulmonary artery; venting the
pulmonary artery during cardiopulmonary bypass; closing the venting
lumen at a vent port at the catheter tube proximal end; partially
retracting the catheter tube distal end from the pulmonary artery
and into the heart; extending the distal wire end distally from the
catheter tube distal end until a conductive end of the pacing wire
enters into conductive engagement with an inner surface of the
heart; and pacing the heart.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/470,779 filed Apr. 1, 2011, the disclosure of
which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of cardiac
surgery, and more particularly, to a catheter used for minimally
invasive cardiac surgery and cardiac pacing during and after the
surgery, and a method of using same for treatment of a patient
undergoing cardiopulmonary bypass surgery.
BACKGROUND OF THE INVENTION
[0003] Minimally invasive cardiac surgery entails the performance
of heart surgery through very small incisions. Due to the limited
size of the incisions, the patient's heart is not completely
exposed. To assure a good or stable heart rhythm during and or
after heart surgery, temporary pacing wires, which electrically
stimulate the heart, are often sewn to the heart surface, and are
used until patient self-pacing is achieved. This can be very
difficult to do in some types of minimally invasive cardiac surgery
cases without increasing the amount of heart dissection that is
done, or increasing the risk of bleeding due to wire placement.
[0004] Minimally invasive cardiac surgery is known to utilize
catheters that are placed into and along the patient's vasculature
to allow safe initiation of cardiopulmonary bypass through
catheters via small incisions. During cardiopulmonary bypass, blood
is removed from the patient's pulmonary artery and the heart is
stopped. The aspirated blood is then oxygenated by a medical
apparatus and is then returned to the patient's arterial system at
an appropriate location spaced from the heart, such as into a
peripheral artery. Once the patient's heart function is undertaken
by the cardiopulmonary bypass machine, the surgery can be safely
performed through small incisions. The bypass procedure generally
utilizes, along with several other catheters, a pulmonary venting
(draining) catheter that is placed into and through the
vasculature, preferably the jugular vein and superior vena cava,
into and through the heart's right atrium and right ventricle, and
into the pulmonary artery. The catheter distal end is then left in
the pulmonary artery so that drainage of blood is by way of the
distally open intake lumen of the catheter. One such pulmonary
venting catheter is the ENDOVENT.RTM. catheter manufactured by
Edwards Lifesciences Corp. (Irvine, Calif.).
[0005] It is known to provide a pacing wire into a patient where
the distal wire end does not require sewing the tip to heart
tissue. By use of a Swan-Ganz PACEPORT.RTM. pacing wire
manufactured by Edwards Lifesciences Corp., a bipolar pacing wire
is introduced into the patient's vasculature and the distal pacing
wire end enters into the heart's right ventricle until it becomes
engaged against the inner surface of the ventricle, termed
intracardiac pacing. This catheter is utilized after pulmonary
venting has been performed and after the venting catheter has been
withdrawn from the patient. The bipolar pacing wire includes two
conductive electrodes that are insulated from each other, one of
which extends to the distal wire end, while the other concludes
proximally of the distal wire end and is exposed to engage nearby
right ventricle tissue. The distal wire end portion is so made to
be extremely flexible so as not to damage the heart (or other)
tissue of the patient, whereby a length of the distal end portion
lies along and against the heart surface for best results. Such
intracardiac pacing is performed during weaning from
cardiopulmonary bypass, and also for post-operative management to
improve cardiac output.
[0006] Generally, in the course of performing minimally invasive
cardiac surgery without the use of pacing wires sewn to the
patient's heart, the pulmonary vent must be exchanged with a pacing
catheter that contains the pacing wire through the use of an
introducing catheter. This requires a sterile technique with
limited access to the head and neck of the patient during the
procedure. Additionally, the heart may not have adequate flow or
any native activity, making it a challenge to advance the pacing
catheter into the right ventricle, and further out into the
pulmonary artery. This may lead to numerous problems, including:
the catheter being positioned in an incorrect location; the
introducing catheter may become bent during the exchange, trapping
the pacing catheter; or, the pacing catheter may loop, knot,
perforate the heart, damage the heart valves, or become entangled
in the chordae tendinae, etc.
[0007] It would be desirable to have a catheter assembly and a
method of use of same that simplifies the minimally invasive
cardiac surgery procedure, reduces the total time needed therefor
in patients, and eliminates the need for additional heart surface
stitches, among other desirable features, as described herein.
SUMMARY OF THE INVENTION
[0008] In one aspect, the present invention is directed in part to
a medical apparatus for use during cardiopulmonary bypass surgery
of a patient. The medical apparatus includes a venting catheter
having a flexible elongate shaft with a distal end, a proximal end,
and an inner venting lumen. The inner venting lumen extends from
the proximal end of the shaft to an inlet port at the distal end of
the shaft. The inlet port is configured to withdraw blood from a
pulmonary artery of the patient. The shaft has a length that allows
the distal end to be positioned in the pulmonary artery with the
proximal end extending transluminally to a central vein and out of
the patient through a puncture in the central vein. The medical
apparatus also includes a pacing wire disposed within the shaft,
and in certain embodiments, the pacing wire may be disposed within
the inner venting lumen. The pacing wire is movable axially along
the shaft between a first, retracted position and a second,
extended position.
[0009] The medical apparatus is insertable into the vasculature and
heart of a patient for pulmonary venting in a venting mode. During
venting mode, the entire pacing wire is within the venting lumen of
the catheter tube at the first position. The medical apparatus is
also used for pacing of the heart in a pacing mode subsequent to
the venting mode. During pacing mode, the pacing wire is extended
from the venting lumen of the catheter tube to the second position
to engage intracardial tissue of the heart for pacing thereof.
[0010] The medical apparatus of the present invention may further
include an inflatable balloon having an interior mounted at the
distal end of the shaft. The venting catheter may further have an
inflation lumen extending from the proximal end to an opening near
the distal end in communication with the interior of the
balloon.
[0011] The pacing wire may include a distal end portion that is
flexible and resilient along its length. This distal end portion
may include a flexible electrode that is exposed when the pacing
wire is in the second position whereby current can be passed
between said electrode and the heart. The distal end portion may
further include a flexible region located adjacent to and
proximally of the flexible electrode. The flexibility of this
region tapers as the region extends proximally. The pacing wire may
also include a section being wound into a coil to form the flexible
region and at least a part of the flexible electrode. The axial
spacing between the turns of the coil at the flexible region may
increase as the flexible region extends proximally. Additionally,
the wire may have a progressively increasing cross-sectional area
as the wire extends proximally in the flexible region. The pacing
wire can also include at last one marking to indicate the axial
position of the pacing wire within the shaft. The pacing wire may
further include a proximal electrode spaced proximally from the
flexible electrode. This proximal electrode may be formed from a
region of a conductive wire having a plurality of coils.
[0012] In another aspect, the present invention is directed in part
to a method for treatment of a patient undergoing cardiopulmonary
bypass surgery. The method includes the steps of: (1) providing an
apparatus having a venting catheter assembly including a flexible
catheter tube having a distal end, a proximal end, and an inner
venting lumen extending from the proximal end to an inlet port at
the distal end configured to withdraw blood from a pulmonary
artery, and further including a pacing wire within the catheter
tube extending to a distal wire end, the pacing wire being movable
axially within and along the catheter tube between first and second
positions; (2) inserting a distal portion of the catheter tube into
the vasculature and into the heart of a patient such that the
catheter tube distal end accesses the pulmonary artery; (3) venting
the pulmonary artery during cardiopulmonary bypass; (4) closing the
venting lumen at a vent port at the catheter tube proximal end; (5)
partially retracting the catheter tube distal end from the
pulmonary artery and into the heart; (6) extending the distal wire
end distally from the catheter tube distal end until a conductive
end of the pacing wire enters into conductive engagement with an
inner surface of the heart; and (7) pacing the heart.
[0013] The apparatus and method of the present invention eliminates
the need to utilize a dedicated catheter for delivery of the pacing
wire to the heart, thus substantially hastening the initiation of
pacing, greatly simplifying the cardiac surgery procedure, reducing
the total time, and also reducing risk to the patient. It also
permits the surgeon to initiate pacing when the surgeon is unable
to exchange catheters due to unusual problems. The present
invention eliminates the need for exchanging the venting catheter
for the pacing catheter near or at the end of surgery, and
eliminates the risk of problems commonly encountered during
catheter exchange, such as inadequate blood flow that challenges
proper advancement of the pacing catheter into the right ventricle,
cardiac perforation or laceration, or post-operative bleeding
related to wire placement or removal. It also eliminates, with
respect to the pacing catheter, encountering the risks involved
during insertion of any catheter through a catheter introducer or
into and along the vasculature to and into the heart.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are incorporated herein and
constitute part of this specification, illustrate the presently
preferred embodiments of the invention, and, together with the
general description given above and the detailed description given
below, serve to explain the features of the invention.
[0015] FIG. 1 is a plan view of a pulmonary venting catheter
assembly containing a pacing wire, in accordance with the present
invention;
[0016] FIG. 2 is a side elevational view partially in section of a
pacing wire of the assembly of FIG. 1;
[0017] FIG. 3 is an isometric view of the distal pacing wire end
extending from the distal end of the venting catheter assembly of
FIG. 1; and
[0018] FIG. 4 is a diagrammatic view of the distal portion of the
venting catheter illustrating the pacing wire extending from the
catheter distal end and in engagement with the inner surface of the
right ventricle, with a previous pulmonary venting position shown
in dashed lines.
DETAILED DESCRIPTION OF THE INVENTION
[0019] In the drawings, like numerals indicate like elements
throughout. Certain terminology is used herein for convenience only
and is not to be taken as a limitation on the present invention.
The terms "proximal" and "distal" refer, respectively, to
directions closer to and away from the operator of the apparatus of
the present invention. The terminology includes the words
specifically mentioned, derivatives thereof, and words of similar
import. The terms and expressions used herein, and the embodiments
illustrated below, are not intended to be exhaustive or to limit
the invention to the precise form disclosed. These terms,
expressions and embodiments are chosen and described to best
explain the principle of the invention and its application and
practical use and to enable others skilled in the art to best
utilize the invention.
[0020] FIG. 1 illustrates a pulmonary venting catheter assembly 10,
including a catheter tube 12 having inserted therethrough a pacing
wire 14, in accordance with the present invention. The catheter
tube 12 includes a distal end 16 and a proximal end 18. The pacing
wire 14 similarly includes a highly flexible distal end portion 20
and a proximal end 22. The illustrated embodiment shows a bipolar
catheter setup. The catheter of the present invention may also
employ a monopolar scheme, which requires that the patient is
appropriately grounded.
[0021] As shown in FIG. 1, the catheter assembly 10 is preferably
provided with an inflatable/deflatable balloon 26 at the distal end
16 of the catheter tube 12. An inflation/deflation lumen (not
shown) extends through catheter tube 12 from balloon 26 to the
proximal end 18 of the catheter tube 12, where an
inflation/deflation port 28 is provided, joining the catheter tube
12 at a hub 30. The balloon 26 is inflated by injecting air through
the inflation port 28, which communicates with the inflation
lumen.
[0022] Additionally, a controllable vent port 32 is attached to the
proximal catheter portion 18 for aspirating blood from the
pulmonary artery during cardiopulmonary bypass. A three-way
stopcock 34 is placed in the proximal end proximally of hub 30,
which serves as a T-piece for both venting and the entry of the
pacing wire 14 into the catheter tube 12. Proximally of the
stopcock 34 is a pressure tubing 36 that can connect to a pressure
sensing line, by which blood pressure in the pulmonary artery is
monitored. Just proximally of the connection of the pressure tubing
36 to the catheter assembly 10 is provided a valve 38 that serves
to occlusively seal around the pacing wire 14 when the valve 38 is
tightened, and also to lock and unlock the axial positioning of the
pacing wire 14 with respect to the catheter tube 12. Sterile
sheathing may be used around the pacing wire and the catheter
tube.
[0023] Referring now to FIG. 2, the bipolar pacing wire 14 is shown
in greater detail in which the highly flexible distal end portion
20 is shown to include a first conductor 40. The first conductor 40
may have a circular cross-section, and is in the form of an
elongated wire having a first section 66 extending from a housing
58 axially through a body 60, a transition section 46 and a
distal-most portion 44. As best shown in FIG. 2, the first section
66 is straight and is covered by an insulation cover 43. The
transition section 46 comprises a plurality of coils 47 which are
spaced apart axially, with the axial spacing between adjacent coils
47 progressively reducing as the transition section 46 extends
distally. This progressive reduction is preferred, but not
essential. The distal most portion 44 comprises a plurality of
contiguous coils 45 and terminates at the distal end 20 of the
pacing wire 14. The coils 45, 47 are wound about an insulative core
42. These coils 45, 47 can be tightly or loosely wound to further
control the flexibility of the pacing wire 14.
[0024] A second conductor 52 concludes at the proximal end 50 of
the transition section 46 and extends proximally thereof, being
preferably flat and ribbon-shaped in cross-section and being wound
about an insulative core section 48 to the proximal end 22 of the
pacing wire 14 in the form of contiguous coils 55, being exposed in
a coaxial section 54 of the pacing wire 14. This exposed coaxial
section 54 forms a proximal electrode. Proximally of the coaxial
section 54, the pacing wire 14 is sheathed in an insulative
covering 56 until concluding in a housing 58, wherein the first and
second conductors 40, 52 are exposed at the end of the pacing wire
14 to be connected to respective leads 60, 62 of a pulse generating
apparatus 64.
[0025] In the illustrated embodiment, a non-conductive elastomer
fills the central space within the coils 55, 47, 45, forming the
insulative core sections 42, 48 about which the first and second
conductors 40, 52 are wound about, and helping insulate the first
conductor 40 from the second conductor 52. In this embodiment, the
presence of the elastomer does not alter the flexibility
characteristics of the pacing wire 14. In addition to forming the
insulative core sections 42, 48, the elastomer encases the coils 47
of the transition section 46 so that only the coils 45 of the
distal-most portion 44 of the first conductor are exposed to define
a distal electrode. In embodiments where an elastomer is not used,
it is preferred to encase the coils 47 of the transition section 46
in a suitable insulation jacket.
[0026] The coaxial section 54, the transition section 46, and the
distal most portion 44 comprise that portion of the pacing wire 14,
as shown in FIG. 4, that extends from the distal end 16 of the
catheter tube 12 when the medical apparatus of the present
invention is being used in pacing mode. Specifically, it is the
exposed area of the distal most portion 44 that forms the electrode
that engages the inner surface of the right ventricle 80 and pace
the heart 82.
[0027] When the assembly is in venting mode, the distal end 20 of
the pacing wire 14 is preferably flush or coterminus with the
distal end 16 of the catheter tube 12. FIG. 3 illustrates the
highly flexible distal end 20 of the pacing wire 14 being projected
to some extent beyond the distal end 16 of catheter tube 12 (shown
with the balloon 26 deflated and transparent to reveal detail). It
is seen that the pacing wire 14 would not interfere with venting
through the catheter tube 12 were it in venting mode (which is
shown in dashed lines in FIG. 4). Also seen are a plurality of side
ports 70 provided at the distal end 16 of the catheter tube 12 that
communicate with the venting lumen 72 there within.
[0028] In venting mode, the catheter tube 12 is introduced into a
central vein by a percutaneous technique such as the Seldinger
technique. The catheter tube 12 is advanced through the central
vein and through a vena cava 88 into the right atrium 86 of the
heart 82. The balloon 26 on the distal end 16 of the catheter tube
12 is then expanded. As the operator pushes distally on the
proximal end of the venting catheter, the flow of blood through the
right side of the heart 82 will tend to guide the distal end 16 and
the expanded balloon 26 from the right atrium 86 through the
tricuspid valve into the right ventricle 80, and from the right
ventricle 80 through the pulmonary valve 90 into the pulmonary
artery 84. The catheter tube 12 is advanced until the distal end 16
and the inlet ports 70 are positioned in the pulmonary artery 84
downstream of the pulmonary valve 90. Pressure monitoring through
pressure ports (not shown) located at the distal end 16 of the
catheter tube 12 in communication with the pressure tubing 36
facilitates proper positioning of the distal end 16 in the
pulmonary artery 84. Accurate placement may be verified by
fluoroscopy or by transesophageal echocardiography. The balloon 26
may then be deflated. Generally, the balloon 26 is used only to
help the catheter tube 12 migrate into the pulmonary artery with
direction provided by the patient's native blood flow. The balloon
26 should not remain inflated or continue to occlude the pulmonary
artery. Leaving the balloon 26 inflated could risk causing
pulmonary artery or branch rupture, or lung infarction.
[0029] Once in position, and upon starting cardiopulmonary bypass,
the blood present in the pulmonary trunk may be vented through the
venting lumen 70 of the catheter tube 12 where it is discharged
through the proximal end 18 of the catheter tube 12, which extends
outside of the patient. The blood withdrawn through the venting
catheter tube 12 then travels through the vent port 32 and may be
routed to a cardiopulmonary bypass unit for oxygenation and return
to the patient's arterial system through an arterial return
catheter (not shown).
[0030] FIG. 4 illustrates the distal end 16 of the pulmonary
venting catheter assembly 10 of the present invention in position
within the right ventricle 80 of heart 82 and in pacing mode after
venting mode is completed. The catheter tube 12 is shown having
been retracted from its position when in venting mode, which is
shown in dashed lines extending through the right ventricle 80 and
into the pulmonary artery 84 where the balloon 26 had been inflated
to occlude the artery. After retraction, the position of the distal
end 16 of the catheter tube 12 is about one to three centimeters
into the right ventricle 80 from the right atrium 86. The distal
end 20 of the pacing wire 14 is shown deployed into its extended
position, protruding from the distal end 16 of the catheter tube 12
until it is in engagement with the inner surface of the right
ventricle 80 so that the distal electrode located at the distal
most portion 44 of the pacing wire 14 of the first conductor 40 can
convey a pacing pulse directly to the heart tissue. Proximally of
the distal electrode is the proximal electrode formed by the
exposed second conductor 52, by which the circuit is completed via
heart tissue and bodily fluids. The catheter tube 12 is seen
extending proximally through the right atrium 86 and the superior
vena cava 88 into the patient's vasculature.
[0031] It is preferable that the catheter tube 12 be marked on its
exposed proximal end portion 18 such that the operator may
determine the precise distance between the distal end 16 of the
catheter tube 12 when in position for venting mode and when in
position for pacing mode, so that retraction is quickly attained
during the surgical procedure. This may easily be determined by
ultrasound guidance prior to venting mode. When the catheter
assembly 10 is in venting mode, the axial position of the pacing
wire 14 within the catheter tube 12 is locked such that the distal
end 40 of the pacing wire is approximately coterminus with the
distal end 16 of catheter tube 12. It is likewise preferable that
the exposed portion of the proximal end of the pacing wire 14 be
marked to indicate the amount by which the pacing wire 14 is to be
extended from the distal end 16 of the catheter tube 12 to
engagement with the inner surface of the right ventricle 80, after
which the pacing wire 14 will again be locked, for pacing mode.
Axial positioning of the pacing wire 14 is attained at valve/lock
38 in the proximal end of the catheter assembly 10, as provided
hereinabove with respect to FIG. 1.
[0032] Tests have shown that the venting/pacing catheter assembly
of the present invention is easily operable by the operator to
convert from venting mode to pacing mode, which can be performed
within two minutes, because exchange of catheters is
eliminated.
[0033] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *